So I bought a non running 1987 305 TPI Camaro a couple weeks back. I've found that it's getting really weak spark and only 9v while cranking (12v key on) to the ignition coil. I've replaced the starter, ignition input wires fusable link, icm, ignition switch, ignition coil, spark plugs, and distributor pickup all both in a hail Mary attempt to fix the issue and also just so that they'd all be new parts. I also cleaned the c100 bulkhead connector and the ignition coil ground. After all of that changed nothing I completely bypassed the ignition input wire all the way to the ignition switch output. Even then I still have 9v while cranking. I'm pretty sure it's a ground somewhere or a power draw but I don't know from where and I don't have any good diagrams showing where to check. I don't know if anyone else has had the same issue or has any ideas but I figured I'd try to reach out for some help.
Edit: it seems like there's a misunderstanding, this is not a poor cranking voltage issue, instead however, it is poor voltage to the ignition system, ie: ignition switch, ignition coil, icm, ect. While cranking the engine and trying to start the Camaro, causing a no start.

 

None of those things affects cranking voltage.

No. With the possible exception of, the negative batt cable connection to the block.

What's the voltage at the battery terminals themselves while cranking?

What's the issue?

 

How cold is the battery and engine when you're cranking? It's pretty cold winter weather many places right now. If the vehicle is outside in the cold then lower cranking voltage is normal.

 

I'm using the battery out of my truck, the car didn't come with a battery, and the guy I bought it from had the same issue, thus why he sold it. My truck starts with this battery just fine, and the battery has about 11v while cranking, and the camaro cranks great and gets fuel, just not spark

 

You still didn't answer the question.

 

Then cranking voltage isn't the issue. Fugheddaboudit and move on.

Not enough info. What year and engine? Is the engine original?

 

it's not cold related, my point mention the truck is that I put it into my Camaro, no start, and then put it in my equally cold truck and have it start up immediately. It's not weather

 

it's the ignition voltage WHILE cranking, not cranking voltage, sorry if that wasn't clear
1987 305 tpi

 

You're too hard to help. I'm out.

 

if you can check the voltage draw on the wires that go to the coil. it sound like you have a damaged wire that is corded and restricting the voltage. look for a pinched or swollen wire. or one that has been chewed on by something rat/ mouse/ squirrel.
good luck

 

many times, the gorund cables on these cars get moved to another place.
this cuases what you are describing.
ive taken jumper cables and added temp grounds from the engine block to the chassis and then to the ground cable to help